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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Cortical regions involved in proactive control of task-set

Stevens, Tobias January 2011 (has links)
This thesis is about what happens in the brain when people switch between tasks. Each task requires a particular assembly of cognitive processes, an orientation of attention and set of rules relating action to input — a "task-set". The research reported used a task-cueing paradigm to study preparatory control of task-set. On each trial a stimulus (a coloured shape) was preceded by a verbal task-cue specifying which task to do (judge the shape or the colour of the stimulus). Reaction time and error rate increase on trials when the task changes relative to trials on which it does not. When the cue stimulus interval (CSI) is increased, this "switch cost" is reduced, indexing a process of task-set reconfiguration in which top-down control is employed to reconfigure the task-set parameters. Effective reconfiguration may also be indicated by a reduction in the "response congruence effect" — poorer performance on stimuli mapped to different responses for the two tasks than for stimuli mapped to the same response. I present six experiments using transcranial magnetic stimulation (TMS), a technique for interfering briefly and harmlessly with neuronal activity in a small region of cortex, to address the question of which brain regions contribute to anticipatory control of task-set as indexed by these behavioural measures. To help guide the selection of candidate brain regions, I first present a review and meta-analysis of neuroimaging studies of task-switching in the literature. Many fMRI studies, comparing brain activation on task-switch and -repeat trials have been published. Some have also tried to isolate activations related specifically to pro-active control of task-set. The activations reported are quite inconsistent over studies. I used a quantitative meta-analysis technique to identify which brain regions are most consistently found by studies reporting switch minus repeat contrasts and which may be specifically important for preparation on switch trials. The experiments examined the effect of stimulating several regions during the long cue-stimulus interval of a task-cueing paradigm, relative to control conditions. A first pair of experiments suggests an important role in proactive task-set control for two regions in dorsal medial frontal cortex, the supplementary motor area (SMA) and an area known as pre-SMA, though the former region appeared to contribute to reducing the switch cost while the latter appeared to reduce the effects of response congruence. In a further three experiments, I examined the role of the right intra-parietal sulcus (rIPS); this appears to play a crucial role in preparation for a task-switch but not post-stimulus task-set reconfiguration. In a final experiment, I used TMS guided by fMRI activations in the same participants to study the effects of stimulation over the left inferior frontal junction (IFJ). The results indicate that a region just anterior to the left IFJ is specifically important for preparing for a switch trial. I discuss the roles that may be played by these three regions in task-set control.
92

Acute Endovascular Reperfusion Therapy in Ischemic Stroke: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Osanai, Toshiya, Pasupuleti, Vinay, Deshpande, Abhishek, Thota, Priyaleela, Roman, Yuani, Hernández, Adrian V., Uchino, Ken 06 May 2015 (has links)
uchinok@ccf.org / Background Randomized controlled trials (RCTs) of endovascular therapy for acute ischemic stroke have had inconsistent results. We evaluated the efficacy and safety of endovascular therapy in published RCTs. Methods We performed a systematic review of RCTs of endovascular therapy with thrombolytic or mechanical reperfusion compared with interventions without endovascular therapy. Primary outcome was the frequency of good functional outcome (modified Rankin scale (mRS) of 0-2 at 90 days) and secondary outcomes were mortality at 90 days and symptomatic intracranial hemorrhage (sICH). Random-effects meta-analysis was performed and the Cochrane risk of bias assessment was used to evaluate quality of evidence. Results Ten studies involving 1,612 subjects were included. Endovascular therapy was not significantly associated with good functional outcome (Relative Risk [RR] =1.17; 95% CI, 0.97 to 1.42; p=0.10 and Absolute Risk Difference [ARD] =7%; 95%CI -0.1% to 14%; p=0.05); heterogeneity was moderate among studies (I2=30%). Mortality was unchanged with endovascular therapy (RR=0.92; 95 % CI, 0.75 to 1.13; p=0.45) and there was no difference in sICH (RR=1.20; 95 % CI, 0.79 to 1.82; p=0.39). The quality of evidence was low for all outcomes and the recommendation is weak for the use of endovascular therapy as per GRADE methodology. Conclusions Intra-arterial therapy did not show significant increase in good outcomes and no changes in either mortality or sICH in patients with acute ischemic stroke. We need further RCTs with better design and quality to evaluate the true efficacy of endovascular therapy.
93

Insulin resistance and endometrial cancer risk: A systematic review and meta-analysis

Hernández, Adrian V., Pasupuleti, Vinay, Benites Zapata, Vicente A., Thota, Priyaleela, Deshpande, Abhishek, Perez Lopez, Faustino R. 25 November 2015 (has links)
Abstract Aim: It has been suggested that chronic hyperinsulinemia from insulin resistance is involved in the etiology of endometrial cancer (EC). We performed a systematic review and meta-analysis to assess whether insulin resistance is associated with the risk of EC. Methods: We searched PubMed-Medline, Embase, Scopus, and Web of Science for articles published from database inception through 30th September 2014. We included all observational studies evaluating components defining insulin resistance in women with and without EC. Quality of the included studies was assessed by NewcastleeOttawa scale. Randomeffects models and inverse variance method were used to meta-analyze the association between insulin resistance components and EC. Results: Twenty-five studies satisfied our inclusion criteria. Fasting insulin levels (13 studies, n Z 4088) were higher in women with EC (mean difference [MD] 33.94 pmol/L, 95% confi- dence interval [CI] 15.04e52.85, p Z 0.0004). No differences were seen in postmenopausal versus pre- and postmenopausal subgroup analysis. Similarly, non-fasting/fasting C-peptide levels (five studies, n Z 1938) were also higher in women with EC (MD 0.14 nmol/L, 95% CI 0.08e0.21, p < 0.00001). Homeostatic model assessment - insulin resistance (HOMA-IR) values (six studies, n Z 1859) in EC patients were significantly higher than in women without EC (MD 1.13, 95% CI 0.20e2.06, p Z 0.02). There was moderate-to-high heterogeneity among the included studies. Conclusion: Currently available epidemiologic evidence is suggestive of significantly higher risk of EC in women with high fasting insulin, non-fasting/fasting C-peptide and HOMAIR values.
94

Visualization for Verification Driven Learning in Database Studies

Kallem, Aditya 17 December 2010 (has links)
This thesis aims at developing a data visualization tool to enhance database learning based on the Verification Driven Learning (VDL) model. The goal of the VDL model is to present abstract concepts in the contexts of real-world systems to students in the early stages of computer science program. In this project, a personnel/training management system has been turned into a learning platform by adding a number of features for visualization and quizzing. We have implemented various tactics to visualize the data manipulation and data retrieval operations in database, as well as the message contents in data messaging channels. The results of our development have been utilized in eight learning cases illustrating the applications of our visualization tool. Each of these learning cases were made by systematically implanting bugs in a functioning component; the students are assigned to identify the bugs and at the same time to learn the structure of the software system active
95

När känslorna får ta rodret : En läsning av John Fowles Den franske löjtnantens kvinna som postmodernt melodrama

Olsson Idman, Ella January 2016 (has links)
This essay is first and foremost an exploration of the melodramatic themes in John Fowles The French Lieutenant’s woman. By defining melodramatic plot events and analyzing the novels postmodern narrative as a melodramatic element in its own right, this study’s purpose is to explain what makes the reader react in a specific way – Or more specifically: feel alienated by the books narrator.                       Throughout the study, I’ve analyzed specific melodramatic examples in The French Lieutenant’s Woman; Its multiple endings, the meta-fictional narrator and its characters and connected them to the melodramatic genre and sensibility in an attempt to define the reader’s emotions towards a seemingly unconventional narrative.
96

Metanálise para Modelos de Regressão / Meta-analysis for Regression Models

Santos, Laryssa Vieira dos 28 October 2016 (has links)
A metanálise tem sido amplamente utilizada em estudos médicos especialmente em revisões sistemáticas de ensaios clínicos aleatorizados. Para modelos de regressão a técnica ainda é muito escassa e limitada. Geralmente trata-se apenas de uma medida baseada nas médias de estimativas pontuais dos diferentes estudos, perdendo-se muita informação dos dados originais. Atualmente torna-se cada vez mais fundamental o uso da metanálise para sumarizar estudos de mesmo objetivo, em razão do avanço da ciência e o desejo de usar o menor número de seres humanos em ensaios clínicos. Utilizando uma medida metanalítica Bayesiana, o objetivo é propor um método genérico e eficiente para realizar metanálise em modelos de regressão. / Meta analysis has been widely used in medical studies especially in systematic reviews of randomized clinical trials. For regression models the technique is still very scarce and limited. Usually it is just a measure based on the average point estimates of dierent studies, losing a lot of information of the original data. Currently it becomes increasingly important to use the meta-analysis to summarize the same objective studies, due to the advancement of science and the desire to use the smallest number of human subjects in clinical trials. Using a meta-analytic Bayesian measure, the objective is to propose a generic and ecient method to perform meta-analysis in regression models.
97

Efficacy of artemisinin derivatives in treating severe malaria in children: A systematic review and meta-analysis

Praygod, George 01 November 2006 (has links)
Student Number : 0416598H - MSc research report - School of Public Health - Faculty of Health Sciences / Background Evidence shows that the efficacy of intravenous quinine, which is the mainstay for treating severe malaria in children, is decreasing. Artemisinin derivatives are the potential replacement for quinine. Their efficacy compared to quinine in treating severe malaria in children is not well known. Objective To assess the efficacy of parenteral artemisinin derivatives versus parenteral quinine in treating severe malaria in children. Search strategy The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 4, 2005), MEDLINE (1966 to October 2005), EMBASE (1980 to October 2005), and LILACS (1982 to October 2005) were searched. Malaria researchers and a pharmaceutical company were contacted. In addition, conference proceedings were also searched. Selection criteria Randomised controlled studies comparing parenteral artemisinin derivatives with parenteral quinine in treating severe malaria in children. All trials had to report mortality as an outcome. Data collection After data were extracted, two individuals independently assessed the trial quality. In addition, information on adverse effects from the studies was also collected. Main results Eleven trials were selected (1455 subjects), nine of them from Africa and the rest from Asia. Allocation concealment was adequate in seven trials (1238 subjects). Overall there was no difference in mortality between artemisinin derivatives and quinine (Risk Ratio= 0.89, 95% confidence interval 0.71 to 1.1). There was no difference in mortality between adequately concealed and inadequately concealed /unconcealed trials (Risk Ratio = 0.93, 95% confidence interval 0.74 to 1.16 and Risk Ratio=0.66, 95% confidence interval 0.36 to 1.22). In Parasite Clearance Time (PCT), though there was no statistical difference between the two groups there was a tendency towards favouring the artemisinin derivatives (weighted mean difference among studies which reported PCT as mean was -4.76 with 95% confidence interval -9.68 to 0.17 and all three studies which reported PCT as median showed that artemisinin derivatives cleared parasites faster than quinine, each had p<0.001). However; when only trials with adequate concealment were considered this potential advantage disappeared. In exploring heterogeneity for PCT, it was shown that study settings (Asia versus Africa) might have been a cause for heterogeneity. The artemisinin derivatives resolved coma faster than quinine (weighted mean difference=-5.32, 95%CI: -8.06 to -2.59), but when only trials with adequate concealment were considered this difference disappeared. Other secondary outcomes i.e. Fever clearance time, Incidence of neurological sequelae, and 28th day cure rate showed no significant difference between artemisinin derivatives and quinine. There was no enough data to make meaningful comparison of adverse effects between the two groups. Conclusions The available evidence suggests that parenteral artemisinin derivatives are as efficacious as quinine in preventing mortality from severe malaria in children.
98

Efficacy and Safety of Bisphosphonates for Postmenopausal Women: A Systematic Review and Network Meta-analysis

Zheng, Carine 26 February 2019 (has links)
Fragility fractures caused by loss of bone mass due to postmenopausal osteoporosis represent a growing morbidity worldwide. Bisphosphonates are first-line medications for fracture treatment and prevention. In the first phase, we updated a Cochrane systematic review of randomized controlled trials on alendronate, assessing its efficacy for five types of fracture prevention, quality of life, and various safety outcomes. In the second phase, we combined indirect and direct evidence to perform a network meta-analysis including alendronate and nine other bisphosphonates evaluating the comparative efficacy and safety of these treatments. Overall, 58 studies were included in the review and 83 studies in the network. Most evidence was of moderate to high quality. Alendronate and zoledronic acid were effective for preventing the most types of fractures, while off-label and unapproved bisphosphonates showed poor efficacy. More evidence is required to evaluate long-term treatment and rare adverse events.
99

Análise comparativa do comportamento de meta-heurísticas populacionais para otimização contínua: uma abordagem baseada em mapas auto-organizáveis / Comparative Analysis of the Behavior of Population Based Metaheuristics for Continuous Optimization: an Approach Based on Self-Organizing Maps (Inglês)

Araújo, Marcelo Lotif 30 August 2012 (has links)
Made available in DSpace on 2019-03-29T23:32:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-30 / The aim of this study is to establish a parallel between four bioinspired metaheuristic algorithms (namely, Genetic Algorithm, Differential Evolution, Particle Swarm Optimization, and Harmony Search), testing them with continuous optimization benchmark functions and assessing them based on data collected about the quality of the solutions they generate and based on the way they explore the search space. Novel techniques are proposed to collect data about the modus operandi of the algorithms using Voronoi Diagrams and through a division of the search space in bi-dimensional regions using Self-Organizing Maps. The use of these maps as a Visual Data Mining tool aims to process the resulting data and identify the available clusters. We wish to understand the influence of parameter calibration on the search behavior of the metaheuristic algorithms, as well as their sensitivity to dimension changes of the optimization functions they are solving. Furthermore, behavior profiles can be established and patterns can be defined, allowing us to analyze in detail the similarities/dissimilarities between the algorithms. All metaheuristics were implemented step-by-step to allow us to understand their inner workings, peculiarities, and also facilitate the tracking of their search behavior along their execution on the optimization problems. Keywords: Bioinspired Metaheuristics. Information Visualization. Visual Data Mining. Self-Organizing Maps. Kohonen Maps. Voronoi Diagrams. / Este trabalho tem por finalidade traçar um paralelo entre quatro algoritmos bio-inspirados de cunho meta-heurístico (a saber: Algoritmo Genético, Evolução Diferencial, Otimização por Enxame de Partículas e Busca Harmônica), testando-os em funções de benchmark de otimização contínua e avaliando-os com base em dados coletados sobre a qualidade das soluções geradas e sobre o modo de exploração do espaço de busca. São propostas aqui técnicas de coleta de informações sobre o modus operandi dos algoritmos que envolvem Diagramas de Voronoi e divisão do espaço de busca em regiões bidimensionais utilizando Mapas Auto-organizáveis. O uso desses mapas como ferramenta de Mineração Visual de Dados tem como objetivo avaliar os dados gerados e identificar os agrupamentos que foram formados. Procuramos entender a influência da alteração dos valores dos parâmetros das meta-heurísticas no seu comportamento ao longo do tempo, bem como a sua sensibilidade às mudanças de dimensão das funções de otimização que estão solucionando. Dessa forma, almeja-se traçar perfis de comportamento e definir a posteriori um padrão para possibilitar a análise mais detalhada das similaridades/dissimilaridades entre as abordagens. Todos os algoritmos utilizados foram implementados passo-a-passo a fim de entender as suas particularidades, esclarecer melhor seus mecanismos internos e facilitar o rastreamento do comportamento dos mesmos no ato da resolução dos problemas. Palavras-chave: Meta-heurísticas Bioinspiradas. Visualização da Informação. Mineração Visual de Dados. Mapas Auto-Organizáveis. Mapas de Kohonen. Diagramas de Voronoi.
100

Re-thinking 'flourishing' as an organic concept of the good : the interpretation of development and the evaluation of life

Griffiths, Jack January 2018 (has links)
This thesis explores the relation between the normative structures brought to bear on the evaluation of life and the way in which the coming-into-being of living organisms is fundamentally understood. It provides a new analysis and critique of the standard concept of ‘flourishing’ in neo-Aristotelian meta-ethics, by uncovering the underlying interpretation of organismic becoming on which it relies, and showing how the turn to a ‘constructivist’ conception of development in contemporary biological theory both disrupts this underlying metaphysics, and provides resources for re-thinking flourishing on a fundamentally different basis. The central claim is that we should turn from a view in which life is given a form to fulfil, and becoming is the process of its fulfilment, to one in which living is the process of creating a way in the world, as life goes along.

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